What are CrCu and CrCuZr?
Both are copper with a small chromium addition, hardened by heat treatment. AMPCO METAL describes the process for CuCrZr as solution annealing, so the chromium dissolves into the copper, then ageing at a lower temperature so fine chromium precipitates form. The result is far harder than pure copper while still conducting well, which is what an electrode needs. Product details are on the chrome copper page.
Why aren't spot-welding electrodes pure copper?
Because pure copper is too soft for repeated force and heat. AMPCO METAL notes that a pure copper electrode cap mushrooms quickly, while CuCrZr caps hold their hardness over far longer runs. As the face mushrooms the contact area grows and current density falls, so welds get smaller and the tip must be dressed or replaced more often.
What does the zirconium in CrCuZr do?
Zirconium improves resistance to softening at temperature. ALCAVIL, an electrode-materials producer, states that C18150 (CuCrZr) has higher softening resistance than C18200 and suits MFDC welders and high-strength galvanized steels, while C18200 (CrCu) is the more economical choice for general work.
| Point | CrCu | CrCuZr |
|---|---|---|
| UNS number | C18200 | C18150 |
| RWMA class | Class 2 | Class 2 |
| Class 2 minimums (AWS J1.3) | ≥ 80 % IACS, ≥ 75 HRB | ≥ 80 % IACS, ≥ 75 HRB |
| Softening resistance | Standard for Class 2 | Higher |
| Typical fit | Low-carbon and galvanized steel, high-volume production | MFDC welders, high-strength galvanized steel |
Should you choose CrCu or CrCuZr?
Choose CrCu for general spot welding where value matters, and CrCuZr for MFDC welders or high-strength galvanized steel. ALCAVIL says the two are interchangeable for most Class 2 work. If your current electrodes wear out early by softening, CrCuZr's higher softening resistance is the reason to consider it.
ALCAVIL also notes that Class 2 suits sheet-to-sheet spot welding but not projection welding of nuts or studs, which needs a different electrode class. If that is your job, say so in your quote request.
What should you confirm with the supplier before ordering?
- The grade and the standard it is made to (for example UNS C18200 or C18150, RWMA Class 2)
- Hardness and conductivity as certified on the mill certificate
- Form and size: round bar, square bar, plate or finished machined parts
- The job: material being welded, welder type and weld rate, so the grade can be checked against it
VAN INTERTRADE supplies both CrCu and CrCuZr. Send the details above from the chrome copper page or request a quote.
Frequently asked questions
- What is CrCuZr?
- CrCuZr is copper-chromium-zirconium (UNS C18150), an age-hardened copper alloy used for RWMA Class 2 spot-welding electrodes. The zirconium gives it better softening resistance than CrCu.
- Can CrCu and CrCuZr be used interchangeably?
- For most Class 2 work, yes, according to ALCAVIL. For MFDC welders or high-strength galvanized steel, ALCAVIL names CrCuZr as the better fit.
- What conductivity and hardness does RWMA Class 2 require?
- ALCAVIL gives the AWS J1.3 Class 2 minimums as 80% IACS and 75 HRB. The actual values of material you buy should be read from the certificate for each lot.
References
- ALCAVIL — RWMA Class 2 C18200 (CuCr) technical data
- ALCAVIL — RWMA Class 2 C18150 (CuCrZr) technical data
- AMPCO METAL Academy — CuCrZr vs. Pure Copper
Sources read on 5 October 2026. Producer data changes; confirm values against the current datasheet before design.